@phdthesis{Schmider2021, author = {Schmider, Stephan}, title = {Was ist HipHop?}, doi = {10.25932/publishup-52375}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-523759}, school = {Universit{\"a}t Potsdam}, pages = {225}, year = {2021}, abstract = {Es handelt sich bei der vorliegenden Dissertation um eine investigative Forschungsarbeit, die sich mit dem dynamisch wandelnden HipHop-Ph{\"a}nomen befasst. Der Autor erl{\"a}utert hierbei die anhaltende Attraktivit{\"a}t des kulturellen Ph{\"a}nomens HipHop und versucht die Tatsache der stetigen Reproduzierbarkeit des HipHops genauer zu erkl{\"a}ren. Daher beginnt er mit einer historischen Diskursanalyse der HipHop-Kultur. Er analysiert hierf{\"u}r die Formen, die Protagonisten und die Diskurse des HipHops, um diesen besser verstehen zu k{\"o}nnen. Durch die Herausarbeitung der genuinen Eigenschaft der Mehrfachkodierbarkeit des HipHops werden g{\"a}ngige Erkl{\"a}rungsmuster aus Wissenschaft und Medien relativiert und kritisiert. Der Autor kombiniert in seiner Studie kultur- und erziehungswissenschaftliche Literatur mit diversen aktuellen und historischen Darstellungen und Bildern. Es werden vor allem bildbasierte Selbstinszenierungen von HipHoppern und Selbstzeugnisse aus narrativen Interviews, die er selbst mit verschiedenen HipHoppern in Deutschland gef{\"u}hrt hat, ausgewertet. Neben den narrativen Interviews dient vor allem die Bildinterpretation nach Bohnsack als Quelle zur Bildung der These der Mehrfachkodierbarkeit. Hierbei werden zwei Bilder der HipHopper Lady Bitch Ray und Kollegah nach Bohnsack (2014) interpretiert und gezeigt wie HipHop neben der lyrischen und der klanglichen Komponente auch visuell inszeniert und produziert wird. Hieraus wird geschlussfolgert, dass es im HipHop m{\"o}glich ist kontr{\"a}re Sichtweisen bei gleichzeitiger Anwendung von typischen Kulturpraktiken wie zum Beispiel dem Boasting darzustellen und zu vermitteln. Die stetige Offenheit des HipHops wird durch Praktiken wie dem Sampling oder dem Battle deutlich und der Autor erkl{\"a}rt, dass durch diese Techniken die generative Eigenschaft der Mehrfachkodierbarkeit hergestellt wird. Damit vertritt er eine Art Baukasten-Theorie, die besagt, dass sich prinzipiell jeder aus dem Baukasten HipHop, je nach Vorliebe, Interesse und Affinit{\"a}t, bedienen kann. Durch die Vielfalt an Meinungen zu HipHop, die der Autor durch die Kodierung der gef{\"u}hrten narrativen Interviews erh{\"a}lt, wird diese These verdeutlicht und es wird klar, dass es sich bei HipHop um mehr als nur eine Mode handelt. HipHop besitzt die prinzipielle M{\"o}glichkeit durch die Offenheit, die er in sich tr{\"a}gt, sich stetig neu zu wandeln und damit an Beliebtheit und Popularit{\"a}t zuzunehmen. Die vorliegende Arbeit erweitert damit die immer gr{\"o}ßer werdende Forschung in den HipHop-Studies und setzt wichtige Akzente um weiter zu forschen und HipHop besser verst{\"a}ndlich zu machen.}, language = {de} } @article{Ehrensperger2017, author = {Ehrensperger, Kathy}, title = {Trajectories and future avenues in Pauline Studies and Jewish-Christian relations}, series = {Journal of beliefs and values : studies in religion \& education}, volume = {38}, journal = {Journal of beliefs and values : studies in religion \& education}, number = {2}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {1361-7672}, doi = {10.1080/13617672.2017.1314988}, pages = {153 -- 158}, year = {2017}, abstract = {William S. Campbell's research on the apostle Paul has been at the forefront of overcoming anti-Jewish interpretations. His career has been characterised by academic rigour and social and interfaith engagement. His interpretive approach is committed to formulating Christian identity in positive relation to others and thus contributes to provide a vital basis for Jewish-Christian and Interfaith relations in general for the future.}, language = {en} } @article{EhrlichKathGaedke2020, author = {Ehrlich, Elias and Kath, Nadja Jeanette and Gaedke, Ursula}, title = {The shape of a defense-growth trade-off governs seasonal trait dynamics in natural phytoplankton}, series = {The ISME journal}, volume = {14}, journal = {The ISME journal}, number = {6}, publisher = {Nature Publishing Group}, address = {London}, issn = {1751-7362}, doi = {10.1038/s41396-020-0619-1}, pages = {1451 -- 1462}, year = {2020}, abstract = {Theory predicts that trade-offs, quantifying costs of functional trait adjustments, crucially affect community trait adaptation to altered environmental conditions, but empirical verification is scarce. We evaluated trait dynamics (antipredator defense, maximum growth rate, and phosphate affinity) of a lake phytoplankton community in a seasonally changing environment, using literature trait data and 21 years of species-resolved high-frequency biomass measurements. The trait data indicated a concave defense-growth trade-off, promoting fast-growing species with intermediate defense. With seasonally increasing grazing pressure, the community shifted toward higher defense levels at the cost of lower growth rates along the trade-off curve, while phosphate affinity explained some deviations from it. We discuss how low fitness differences of species, inferred from model simulations, in concert with stabilizing mechanisms, e.g., arising from further trait dimensions, may lead to the observed phytoplankton diversity. In conclusion, quantifying trade-offs is key for predictions of community trait adaptation and biodiversity under environmental change.}, language = {en} } @misc{EhrlichKathGaedke2020, author = {Ehrlich, Elias and Kath, Nadja Jeanette and Gaedke, Ursula}, title = {The shape of a defense-growth trade-off governs seasonal trait dynamics in natural phytoplankton}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {6}, issn = {1866-8372}, doi = {10.25932/publishup-51395}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-513956}, pages = {14}, year = {2020}, abstract = {Theory predicts that trade-offs, quantifying costs of functional trait adjustments, crucially affect community trait adaptation to altered environmental conditions, but empirical verification is scarce. We evaluated trait dynamics (antipredator defense, maximum growth rate, and phosphate affinity) of a lake phytoplankton community in a seasonally changing environment, using literature trait data and 21 years of species-resolved high-frequency biomass measurements. The trait data indicated a concave defense-growth trade-off, promoting fast-growing species with intermediate defense. With seasonally increasing grazing pressure, the community shifted toward higher defense levels at the cost of lower growth rates along the trade-off curve, while phosphate affinity explained some deviations from it. We discuss how low fitness differences of species, inferred from model simulations, in concert with stabilizing mechanisms, e.g., arising from further trait dimensions, may lead to the observed phytoplankton diversity. In conclusion, quantifying trade-offs is key for predictions of community trait adaptation and biodiversity under environmental change.}, language = {en} } @phdthesis{May2013, author = {May, Felix}, title = {Spatial models of plant diversity and plant functional traits : towards a better understanding of plant community dynamics in fragmented landscapes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68444}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The fragmentation of natural habitat caused by anthropogenic land use changes is one of the main drivers of the current rapid loss of biodiversity. In face of this threat, ecological research needs to provide predictions of communities' responses to fragmentation as a prerequisite for the effective mitigation of further biodiversity loss. However, predictions of communities' responses to fragmentation require a thorough understanding of ecological processes, such as species dispersal and persistence. Therefore, this thesis seeks an improved understanding of community dynamics in fragmented landscapes. In order to approach this overall aim, I identified key questions on the response of plant diversity and plant functional traits to variations in species' dispersal capability, habitat fragmentation and local environmental conditions. All questions were addressed using spatially explicit simulations or statistical models. In chapter 2, I addressed scale-dependent relationships between dispersal capability and species diversity using a grid-based neutral model. I found that the ratio of survey area to landscape size is an important determinant of scale-dependent dispersal-diversity relationships. With small ratios, the model predicted increasing dispersal-diversity relationships, while decreasing dispersal-diversity relationships emerged, when the ratio approached one, i.e. when the survey area approached the landscape size. For intermediate ratios, I found a U-shaped pattern that has not been reported before. With this study, I unified and extended previous work on dispersal-diversity relationships. In chapter 3, I assessed the type of regional plant community dynamics for the study area in the Southern Judean Lowlands (SJL). For this purpose, I parameterised a multi-species incidence-function model (IFM) with vegetation data using approximate Bayesian computation (ABC). I found that the type of regional plant community dynamics in the SJL is best characterized as a set of isolated "island communities" with very low connectivity between local communities. Model predictions indicated a significant extinction debt with 33\% - 60\% of all species going extinct within 1000 years. In general, this study introduces a novel approach for combining a spatially explicit simulation model with field data from species-rich communities. In chapter 4, I first analysed, if plant functional traits in the SJL indicate trait convergence by habitat filtering and trait divergence by interspecific competition, as predicted by community assembly theory. Second, I assessed the interactive effects of fragmentation and the south-north precipitation gradient in the SJL on community-mean plant traits. I found clear evidence for trait convergence, but the evidence for trait divergence fundamentally depended on the chosen null-model. All community-mean traits were significantly associated with the precipitation gradient in the SJL. The trait associations with fragmentation indices (patch size and connectivity) were generally weaker, but statistically significant for all traits. Specific leaf area (SLA) and plant height were consistently associated with fragmentation indices along the precipitation gradient. In contrast, seed mass and seed number were interactively influenced by fragmentation and precipitation. In general, this study provides the first analysis of the interactive effects of climate and fragmentation on plant functional traits. Overall, I conclude that the spatially explicit perspective adopted in this thesis is crucial for a thorough understanding of plant community dynamics in fragmented landscapes. The finding of contrasting responses of local diversity to variations in dispersal capability stresses the importance of considering the diversity and composition of the metacommunity, prior to implementing conservation measures that aim at increased habitat connectivity. The model predictions derived with the IFM highlight the importance of additional natural habitat for the mitigation of future species extinctions. In general, the approach of combining a spatially explicit IFM with extensive species occupancy data provides a novel and promising tool to assess the consequences of different management scenarios. The analysis of plant functional traits in the SJL points to important knowledge gaps in community assembly theory with respect to the simultaneous consequences of habitat filtering and competition. In particular, it demonstrates the importance of investigating the synergistic consequences of fragmentation, climate change and land use change on plant communities. I suggest that the integration of plant functional traits and of species interactions into spatially explicit, dynamic simulation models offers a promising approach, which will further improve our understanding of plant communities and our ability to predict their dynamics in fragmented and changing landscapes.}, language = {en} } @article{GuillHuelsemannKlauschies2021, author = {Guill, Christian and H{\"u}lsemann, Janne and Klauschies, Toni}, title = {Self-organised pattern formation increases local diversity in metacommunities}, series = {Ecology letters}, volume = {24}, journal = {Ecology letters}, number = {12}, publisher = {Wiley-Blackwell}, address = {Oxford}, issn = {1461-023X}, doi = {10.1111/ele.13880}, pages = {2624 -- 2634}, year = {2021}, abstract = {Self-organised formation of spatial patterns is known from a variety of different ecosystems, yet little is known about how these patterns affect the diversity of communities. Here, we use a food chain model in which autotroph diversity is described by a continuous distribution of a trait that affects both growth and defence against heterotrophs. On isolated patches, diversity is always lost over time due to stabilising selection, and the local communities settle on one of two alternative stable community states that are characterised by a dominance of either defended or undefended species. In a metacommunity context, dispersal can destabilise these states and complex spatio-temporal patterns in the species' abundances emerge. The resulting biomass-trait feedback increases local diversity by an order of magnitude compared to scenarios without self-organised pattern formation, thereby maintaining the ability of communities to adapt to potential future changes in biotic or abiotic environmental conditions.}, language = {en} } @misc{FosterGarvieWeissetal.2020, author = {Foster, William J. and Garvie, Christopher L. and Weiss, Anna M. and Muscente, A. Drew and Aberhan, Martin and Counts, John W. and Martindale, Rowan C.}, title = {Resilience of marine invertebrate communities during the early Cenozoic hyperthermals}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1}, issn = {1866-8372}, doi = {10.25932/publishup-51601}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-516011}, pages = {13}, year = {2020}, abstract = {The hyperthermal events of the Cenozoic, including the Paleocene-Eocene Thermal Maximum, provide an opportunity to investigate the potential effects of climate warming on marine ecosystems. Here, we examine the shallow benthic marine communities preserved in the late Cretaceous to Eocene strata on the Gulf Coastal Plain (United States). In stark contrast to the ecological shifts following the end-Cretaceous mass extinction, our data show that the early Cenozoic hyperthermals did not have a long-term impact on the generic diversity nor composition of the Gulf Coastal Plain molluscan communities. We propose that these communities were resilient to climate change because molluscs are better adapted to high temperatures than other taxa, as demonstrated by their physiology and evolutionary history. In terms of resilience, these communities differ from other shallow-water carbonate ecosystems, such as reef communities, which record significant changes during the early Cenozoic hyperthermals. These data highlight the strikingly different responses of community types, i.e., the almost imperceptible response of molluscs versus the marked turnover of foraminifera and reef faunas. The impact on molluscan communities may have been low because detrimental conditions did not devastate the entire Gulf Coastal Plain, allowing molluscs to rapidly recolonise vacated areas once harsh environmental conditions ameliorated.}, language = {en} } @article{FosterGarvieWeissetal.2020, author = {Foster, William J. and Garvie, Christopher L. and Weiss, Anna M. and Muscente, A. Drew and Aberhan, Martin and Counts, John W. and Martindale, Rowan C.}, title = {Resilience of marine invertebrate communities during the early Cenozoic hyperthermals}, series = {Scientific Reports}, volume = {10}, journal = {Scientific Reports}, number = {1}, publisher = {Springer Nature}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-020-58986-5}, pages = {1 -- 11}, year = {2020}, abstract = {The hyperthermal events of the Cenozoic, including the Paleocene-Eocene Thermal Maximum, provide an opportunity to investigate the potential effects of climate warming on marine ecosystems. Here, we examine the shallow benthic marine communities preserved in the late Cretaceous to Eocene strata on the Gulf Coastal Plain (United States). In stark contrast to the ecological shifts following the end-Cretaceous mass extinction, our data show that the early Cenozoic hyperthermals did not have a long-term impact on the generic diversity nor composition of the Gulf Coastal Plain molluscan communities. We propose that these communities were resilient to climate change because molluscs are better adapted to high temperatures than other taxa, as demonstrated by their physiology and evolutionary history. In terms of resilience, these communities differ from other shallow-water carbonate ecosystems, such as reef communities, which record significant changes during the early Cenozoic hyperthermals. These data highlight the strikingly different responses of community types, i.e., the almost imperceptible response of molluscs versus the marked turnover of foraminifera and reef faunas. The impact on molluscan communities may have been low because detrimental conditions did not devastate the entire Gulf Coastal Plain, allowing molluscs to rapidly recolonise vacated areas once harsh environmental conditions ameliorated.}, language = {en} } @phdthesis{Heise2017, author = {Heise, Janine}, title = {Phylogenetic and physiological characterization of deep-biosphere microorganisms in El'gygytgyn Crater Lake sediments}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-403436}, school = {Universit{\"a}t Potsdam}, pages = {117}, year = {2017}, abstract = {The existence of diverse and active microbial ecosystems in the deep subsurface - a biosphere that was originally considered devoid of life - was discovered in multiple microbiological studies. However, most of the studies are restricted to marine ecosystems, while our knowledge about the microbial communities in the deep subsurface of lake systems and their potentials to adapt to changing environmental conditions is still fragmentary. This doctoral thesis aims to build up a unique data basis for providing the first detailed high-throughput characterization of the deep biosphere of lacustrine sediments and to emphasize how important it is to differentiate between the living and the dead microbial community in deep biosphere studies. In this thesis, up to 3.6 Ma old sediments (up to 317 m deep) of the El'gygytgyn Crater Lake were examined, which represents the oldest terrestrial climate record of the Arctic. Combining next generation sequencing with detailed geochemical characteristics and other environmental parameters, the microbial community composition was analyzed in regard to changing climatic conditions within the last 3.6 Ma to 1.0 Ma (Pliocene and Pleistocene). DNA from all investigated sediments was successfully extracted and a surprisingly diverse (6,910 OTUs) and abundant microbial community in the El'gygytgyn deep sediments were revealed. The bacterial abundance (10³-10⁶ 16S rRNA copies g⁻¹ sediment) was up to two orders of magnitudes higher than the archaeal abundance (10¹-10⁵) and fluctuates with the Pleistocene glacial/interglacial cyclicality. Interestingly, a strong increase in the microbial diversity with depth was observed (approximately 2.5 times higher diversity in Pliocene sediments compared to Pleistocene sediments). The increase in diversity with depth in the Lake El'gygytgyn is most probably caused by higher sedimentary temperatures towards the deep sediment layers as well as an enhanced temperature-induced intra-lake bioproductivity and higher input of allochthonous organic-rich material during Pliocene climatic conditions. Moreover, the microbial richness parameters follow the general trends of the paleoclimatic parameters, such as the paleo-temperature and paleo-precipitation. The most abundant bacterial representatives in the El'gygytgyn deep biosphere are affiliated with the phyla Proteobacteria, Actinobacteria, Bacteroidetes, and Acidobacteria, which are also commonly distributed in the surrounding permafrost habitats. The predominated taxon was the halotolerant genus Halomonas (in average 60\% of the total reads per sample). Additionally, this doctoral thesis focuses on the live/dead differentiation of microbes in cultures and environmental samples. While established methods (e.g., fluorescence in situ hybridization, RNA analyses) are not applicable to the challenging El'gygytgyn sediments, two newer methods were adapted to distinguish between DNA from live cells and free (extracellular, dead) DNA: the propidium monoazide (PMA) treatment and the cell separation adapted for low amounts of DNA. The applicability of the DNA-intercalating dye PMA was successfully evaluated to mask free DNA of different cultures of methanogenic archaea, which play a major role in the global carbon cycle. Moreover, an optimal procedure to simultaneously treat bacteria and archaea was developed using 130 µM PMA and 5 min of photo-activation with blue LED light, which is also applicable on sandy environmental samples with a particle load of ≤ 200 mg mL⁻¹. It was demonstrated that the soil texture has a strong influence on the PMA treatment in particle-rich samples and that in particular silt and clay-rich samples (e.g., El'gygytgyn sediments) lead to an insufficient shielding of free DNA by PMA. Therefore, a cell separation protocol was used to distinguish between DNA from live cells (intracellular DNA) and extracellular DNA in the El'gygytgyn sediments. While comparing these two DNA pools with a total DNA pool extracted with a commercial kit, significant differences in the microbial composition of all three pools (mean distance of relative abundance: 24.1\%, mean distance of OTUs: 84.0\%) was discovered. In particular, the total DNA pool covers significantly fewer taxa than the cell-separated DNA pools and only inadequately represents the living community. Moreover, individual redundancy analyses revealed that the microbial community of the intra- and extracellular DNA pool are driven by different environmental factors. The living community is mainly influenced by life-dependent parameters (e.g., sedimentary matrix, water availability), while the extracellular DNA is dependent on the biogenic silica content. The different community-shaping parameters and the fact, that a redundancy analysis of the total DNA pool explains significantly less variance of the microbial community, indicate that the total DNA represents a mixture of signals of the live and dead microbial community. This work provides the first fundamental data basis of the diversity and distribution of microbial deep biosphere communities of a lake system over several million years. Moreover, it demonstrates the substantial importance of extracellular DNA in old sediments. These findings may strongly influence future environmental community analyses, where applications of live/dead differentiation avoid incorrect interpretations due to a failed extraction of the living microbial community or an overestimation of the past community diversity in the course of total DNA extraction approaches.}, language = {en} } @article{WiesnerLoxdaleKoehleretal.2011, author = {Wiesner, Kerstin R. and Loxdale, Hugh D. and K{\"o}hler, G{\"u}nter and Schneider, Anja R. R. and Tiedemann, Ralph and Weisser, Wolfgang W.}, title = {Patterns of local and regional genetic structuring in the meadow grasshopper, Chorthippus parallelus (Orthoptera: Acrididae), in Central Germany revealed using microsatellite markers}, series = {Biological journal of the Linnean Society : a journal of evolution}, volume = {103}, journal = {Biological journal of the Linnean Society : a journal of evolution}, number = {4}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {0024-4066}, doi = {10.1111/j.1095-8312.2011.01698.x}, pages = {875 -- 890}, year = {2011}, abstract = {The meadow grasshopper, Chorthippus parallelus (Zetterstedt), is common and widespread in Central Europe, with a low dispersal range per generation. A population study in Central Germany (Frankenwald and Thuringer Schiefergebirge) showed strong interpopulation differences in abundance and individual fitness. We examined genetic variability using microsatellite markers within and between 22 populations in a short-to long-distance sampling (19 populations, Frankenwald, Schiefergebirge, as well as a southern transect), and in the Erzgebirge region (three populations), with the latter aiming to check for effects as a result of historical forest cover. Of the 671 C. parallelus captured, none was macropterous (functionally winged). All populations showed a high level of expected and observed heterozygosity (mean 0.80-0.90 and 0.60-0.75, respectively), whereas there was evidence of inbreeding (F(IS) values all positive). Allelic richness for all locus-population combinations was high (mean 9.3-11.2), whereas alleles per locus ranged from 15-62. At a local level, genic and genotypic differences were significant. Pairwise F(ST) values were in the range 0.00-0.04, indicating little interpopulation genetic differentiation. Similarly, the calculated gene flow was very high, based on the respective F(ST) (19.5) and using private alleles (7.7). A Neighbour-joining tree using Nei's D(A) and principal coordinate analysis separated two populations that were collected in the Erzgebirge region. Populations from this region may have escaped the effects of the historical forest cover. The visualization of the spatial arrangement of genotypes revealed one geographical barrier to gene flow in the short-distance sampling.}, language = {en} } @phdthesis{Wagner2007, author = {Wagner, Dirk}, title = {Microbial perspectives of the methane cycle in permafrost ecosystems in the Eastern Siberian Arctic : implications for the global methane budget}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-15434}, school = {Universit{\"a}t Potsdam}, year = {2007}, abstract = {The Arctic plays a key role in Earth's climate system as global warming is predicted to be most pronounced at high latitudes and because one third of the global carbon pool is stored in ecosystems of the northern latitudes. In order to improve our understanding of the present and future carbon dynamics in climate sensitive permafrost ecosystems, the present study concentrates on investigations of microbial controls of methane fluxes, on the activity and structure of the involved microbial communities, and on their response to changing environmental conditions. For this purpose an integrated research strategy was applied, which connects trace gas flux measurements to soil ecological characterisation of permafrost habitats and molecular ecological analyses of microbial populations. Furthermore, methanogenic archaea isolated from Siberian permafrost have been used as potential keystone organisms for studying and assessing life under extreme living conditions. Long-term studies on methane fluxes were carried out since 1998. These studies revealed considerable seasonal and spatial variations of methane emissions for the different landscape units ranging from 0 to 362 mg m-2 d-1. For the overall balance of methane emissions from the entire delta, the first land cover classification based on Landsat images was performed and applied for an upscaling of the methane flux data sets. The regionally weighted mean daily methane emissions of the Lena Delta (10 mg m-2 d-1) are only one fifth of the values calculated for other Arctic tundra environments. The calculated annual methane emission of the Lena Delta amounts to about 0.03 Tg. The low methane emission rates obtained in this study are the result of the used remotely sensed high-resolution data basis, which provides a more realistic estimation of the real methane emissions on a regional scale. Soil temperature and near soil surface atmospheric turbulence were identified as the driving parameters of methane emissions. A flux model based on these variables explained variations of the methane budget corresponding to continuous processes of microbial methane production and oxidation, and gas diffusion through soil and plants reasonably well. The results show that the Lena Delta contributes significantly to the global methane balance because of its extensive wetland areas. The microbiological investigations showed that permafrost soils are colonized by high numbers of microorganisms. The total biomass is comparable to temperate soil ecosystems. Activities of methanogens and methanotrophs differed significantly in their rates and distribution patterns along both the vertical profiles and the different investigated soils. The methane production rates varied between 0.3 and 38.9 nmol h-1 g-1, while the methane oxidation ranged from 0.2 to 7.0 nmol h-1 g-1. Phylogenetic analyses of methanogenic communities revealed a distinct diversity of methanogens affiliated to Methanomicrobiaceae, Methanosarcinaceae and Methanosaetaceae, which partly form four specific permafrost clusters. The results demonstrate the close relationship between methane fluxes and the fundamental microbiological processes in permafrost soils. The microorganisms do not only survive in their extreme habitat but also can be metabolic active under in situ conditions. It was shown that a slight increase of the temperature can lead to a substantial increase in methanogenic activity within perennially frozen deposits. In case of degradation, this would lead to an extensive expansion of the methane deposits with their subsequent impacts on total methane budget. Further studies on the stress response of methanogenic archaea, especially Methanosarcina SMA-21, isolated from Siberian permafrost, revealed an unexpected resistance of the microorganisms against unfavourable living conditions. A better adaptation to environmental stress was observed at 4 °C compared to 28 °C. For the first time it could be demonstrated that methanogenic archaea from terrestrial permafrost even survived simulated Martian conditions. The results show that permafrost methanogens are more resistant than methanogens from non-permafrost environments under Mars-like climate conditions. Microorganisms comparable to methanogens from terrestrial permafrost can be seen as one of the most likely candidates for life on Mars due to their physiological potential and metabolic specificity.}, language = {en} } @phdthesis{Tschoepe2007, author = {Tsch{\"o}pe, Okka}, title = {Managing open habitats for species conservation : the role of wild ungulate grazing, small-scale disturbances, and scale}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-13218}, school = {Universit{\"a}t Potsdam}, year = {2007}, abstract = {During the last decades, the global change of the environment has caused a dramatic loss of habitats and species. In Central Europe, open habitats are particularly affected. The main objective of this thesis was to experimentally test the suitability of wild megaherbivore grazing as a conservation tool to manage open habitats. We studied the effect of wild ungulates in a 160 ha game preserve in NE Germany in three successional stages (i) Corynephorus canescens-dominated grassland, (ii) ruderal tall forb vegetation dominated by Tanacetum vulgare and (iii) Pinus sylvestris-pioneer forest over three years. Our results demonstrate that wild megaherbivores considerably affected species composition and delayed successional pathways in open habitats. Grazing effects differed considerably between successional stages: species richness was higher in grazed ruderal and pioneer forest plots, but not in the Corynephorus sites. Species composition changed significantly in the Corynephorus and ruderal sites. Grazed ruderal sites had turned into sites with very short vegetation dominated by Agrostis spp. and the moss Brachythecium albicans, most species did not flower. Woody plant cover was significantly affected only in the pioneer forest sites. Young pine trees were severely damaged and tree height was considerably reduced, leading to a "Pinus-macchie"-appearance. Ecological patterns and processes are known to vary with spatial scale. Since grazing by megaherbivores has a strong spatial component, the scale of monitoring success of grazing may largely differ among and within different systems. Thus, the second aim of this thesis was to test whether grazing effects are consistent over different spatial scales, and to give recommendations for appropriate monitoring scales. For this purpose, we studied grazing effects on plant community structure using multi-scale plots that included three nested spatial scales (0.25 m2, 4 m2, and 40 m2). Over all vegetation types, the scale of observation directly affected grazing effects on woody plant cover and on floristic similarity, but not on the proportion of open soil and species richness. Grazing effects manifested at small scales regarding floristic similarity in pioneer forest and ruderal sites and regarding species richness in ruderal sites. The direction of scale-effects on similarity differed between vegetation types: Grazing effects on floristic similarity in the Corynephorus sites were significantly higher at the medium and large scale, while in the pioneer forest sites they were significantly higher at the smallest scale. Disturbances initiate vegetation changes by creating gaps and affecting colonization and extinction rates. The third intention of the thesis was to investigate the effect of small-scale disturbances on the species-level. In a sowing experiment, we studied early establishment probabilities of Corynephorus canescens, a key species of open sandy habitats. Applying two different regimes of mechanical ground disturbance (disturbed and undisturbed) in the three successional stages mentioned above, we focused on the interactive effects of small-scale disturbances, successional stage and year-to-year variation. Disturbance led to higher emergence in a humid and to lower emergence in a very dry year. Apparently, when soil moisture was sufficient, the main factor limiting C. canescens establishment was competition, while in the dry year water became the limiting factor. Survival rates were not affected by disturbance. In humid years, C. canescens emerged in higher numbers in open successional stages while in the dry year, emergence rates were higher in late stages, suggesting an important role of late successional stages for the persistence of C. canescens. We conclude that wild ungulate grazing is a useful tool to slow down succession and to preserve a species-rich, open landscape, because it does not only create disturbances, thereby supporting early successional stages, but at the same time efficiently controls woody plant cover. However, wild ungulate grazing considerably changed the overall appearance of the landscape. Additional measures like shifting exclosures might be necessary to allow vulnerable species to flower and reproduce. We further conclude that studying grazing impacts on a range of scales is crucial, since different parameters are affected at different spatial scales. Larger scales are suitable for assessing grazing impact on structural parameters like the proportion of open soil or woody plant cover, whereas species richness and floristic similarity are affected at smaller scales. Our results further indicate that the optimal strategy for promoting C. canescens is to apply disturbances just before seed dispersal and not during dry years. Further, at the landscape scale, facilitation by late successional species may be an important mechanism for the persistence of protected pioneer species.}, language = {en} } @misc{DrygalaKorablevAnsorgeetal.2016, author = {Drygala, Frank and Korablev, Nikolay and Ansorge, Hermann and Fickel, J{\"o}rns and Isomursu, Marja and Elmeros, Morten and Kowalczyk, Rafał and Baltrunaite, Laima and Balciauskas, Linas and Saarma, Urmas and Schulze, Christoph and Borkenhagen, Peter and Frantz, Alain C.}, title = {Homogenous population genetic structure of the non-native raccoon dog (Nyctereutes procyonoides) in Europe as a result of rapid population expansion}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {540}, issn = {1866-8372}, doi = {10.25932/publishup-41092}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-410921}, pages = {17}, year = {2016}, abstract = {The extent of gene flow during the range expansion of non-native species influences the amount of genetic diversity retained in expanding populations. Here, we analyse the population genetic structure of the raccoon dog (Nyctereutes procyonoides) in north-eastern and central Europe. This invasive species is of management concern because it is highly susceptible to fox rabies and an important secondary host of the virus. We hypothesized that the large number of introduced animals and the species' dispersal capabilities led to high population connectivity and maintenance of genetic diversity throughout the invaded range. We genotyped 332 tissue samples from seven European countries using 16 microsatellite loci. Different algorithms identified three genetic clusters corresponding to Finland, Denmark and a large 'central' population that reached from introduction areas in western Russia to northern Germany. Cluster assignments provided evidence of long-distance dispersal. The results of an Approximate Bayesian Computation analysis supported a scenario of equal effective population sizes among different pre-defined populations in the large central cluster. Our results are in line with strong gene flow and secondary admixture between neighbouring demes leading to reduced genetic structuring, probably a result of its fairly rapid population expansion after introduction. The results presented here are remarkable in the sense that we identified a homogenous genetic cluster inhabiting an area stretching over more than 1500km. They are also relevant for disease management, as in the event of a significant rabies outbreak, there is a great risk of a rapid virus spread among raccoon dog populations.}, language = {en} } @misc{RomeroMunozFandosBenitezLopezetal.2020, author = {Romero-Munoz, Alfredo and Fandos, Guillermo and Ben{\´i}tez-L{\´o}pez, Ana and Kuemmerle, Tobias}, title = {Habitat destruction and overexploitation drive widespread declines in all facets of mammalian diversity in the Gran Chaco}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {4}, issn = {1866-8372}, doi = {10.25932/publishup-56769}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-567696}, pages = {15}, year = {2020}, abstract = {Global biodiversity is under high and rising anthropogenic pressure. Yet, how the taxonomic, phylogenetic, and functional facets of biodiversity are affected by different threats over time is unclear. This is particularly true for the two main drivers of the current biodiversity crisis: habitat destruction and overexploitation. We provide the first long-term assessment of multifaceted biodiversity changes caused by these threats for any tropical region. Focussing on larger mammals in South America's 1.1 million km(2) Gran Chaco region, we assessed changes in multiple biodiversity facets between 1985 and 2015, determined which threats drive those changes, and identified remaining key areas for all biodiversity facets. Using habitat and threat maps, we found, first, that between 1985 and 2015 taxonomic (TD), phylogenetic (PD) and functional (FD) diversity all declined drastically across over half of the area assessed. FD declined about 50\% faster than TD and PD, and these declines were mainly driven by species loss, rather than species turnover. Second, habitat destruction, hunting, and both threats together contributed similar to 57\%, similar to 37\%, and similar to 6\% to overall facet declines, respectively. However, hunting pressure increased where TD and PD declined most strongly, whereas habitat destruction disproportionally contributed to FD declines. Third, just 23\% of the Chaco would have to be protected to safeguard the top 17\% of all three facets. Our findings uncover a widespread impoverishment of mammal species richness, evolutionary history, and ecological functions across broad areas of the Chaco due to increasing habitat destruction and hunting. Moreover, our results pinpoint key areas that should be preserved and managed to maintain all facets of mammalian diversity across the Chaco. More generally, our work highlights how long-term changes in biodiversity facets can be assessed and attributed to specific threats, to better understand human impacts on biodiversity and to guide conservation planning to mitigate them.}, language = {en} } @article{RomeroMunozFandosBenitezLopezetal.2020, author = {Romero-Munoz, Alfredo and Fandos, Guillermo and Ben{\´i}tez-L{\´o}pez, Ana and Kuemmerle, Tobias}, title = {Habitat destruction and overexploitation drive widespread declines in all facets of mammalian diversity in the Gran Chaco}, series = {Global change biology}, volume = {27}, journal = {Global change biology}, number = {4}, publisher = {Wiley}, address = {Hoboken}, issn = {1354-1013}, doi = {10.1111/gcb.15418}, pages = {755 -- 767}, year = {2020}, abstract = {Global biodiversity is under high and rising anthropogenic pressure. Yet, how the taxonomic, phylogenetic, and functional facets of biodiversity are affected by different threats over time is unclear. This is particularly true for the two main drivers of the current biodiversity crisis: habitat destruction and overexploitation. We provide the first long-term assessment of multifaceted biodiversity changes caused by these threats for any tropical region. Focussing on larger mammals in South America's 1.1 million km(2) Gran Chaco region, we assessed changes in multiple biodiversity facets between 1985 and 2015, determined which threats drive those changes, and identified remaining key areas for all biodiversity facets. Using habitat and threat maps, we found, first, that between 1985 and 2015 taxonomic (TD), phylogenetic (PD) and functional (FD) diversity all declined drastically across over half of the area assessed. FD declined about 50\% faster than TD and PD, and these declines were mainly driven by species loss, rather than species turnover. Second, habitat destruction, hunting, and both threats together contributed similar to 57\%, similar to 37\%, and similar to 6\% to overall facet declines, respectively. However, hunting pressure increased where TD and PD declined most strongly, whereas habitat destruction disproportionally contributed to FD declines. Third, just 23\% of the Chaco would have to be protected to safeguard the top 17\% of all three facets. Our findings uncover a widespread impoverishment of mammal species richness, evolutionary history, and ecological functions across broad areas of the Chaco due to increasing habitat destruction and hunting. Moreover, our results pinpoint key areas that should be preserved and managed to maintain all facets of mammalian diversity across the Chaco. More generally, our work highlights how long-term changes in biodiversity facets can be assessed and attributed to specific threats, to better understand human impacts on biodiversity and to guide conservation planning to mitigate them.}, language = {en} } @article{HuangHerzschuhPestryakovaetal.2020, author = {Huang, Sichao and Herzschuh, Ulrike and Pestryakova, Luidmila Agafyevna and Zimmermann, Heike Hildegard and Davydova, Paraskovya and Biskaborn, Boris and Shevtsova, Iuliia and Stoof-Leichsenring, Kathleen Rosemarie}, title = {Genetic and morphologic determination of diatom community composition in surface sediments from glacial and thermokarst lakes in the Siberian Arctic}, series = {Journal of paleolimnolog}, volume = {64}, journal = {Journal of paleolimnolog}, number = {3}, publisher = {Springer}, address = {Dordrecht}, issn = {0921-2728}, doi = {10.1007/s10933-020-00133-1}, pages = {225 -- 242}, year = {2020}, abstract = {Lakes cover large parts of the climatically sensitive Arctic landscape and respond rapidly to environmental change. Arctic lakes have different origins and include the predominant thermokarst lakes, which are small, young and highly dynamic, as well as large, old and stable glacial lakes. Freshwater diatoms dominate the primary producer community in these lakes and can be used to detect biotic responses to climate and environmental change. We used specific diatom metabarcoding on sedimentary DNA, combined with next-generation sequencing and diatom morphology, to assess diatom diversity in five glacial and 15 thermokarst lakes within the easternmost expanse of the Siberian treeline ecotone in Chukotka, Russia. We obtained 163 verified diatom sequence types and identified 176 diatom species morphologically. Although there were large differences in taxonomic assignment using the two approaches, they showed similar high abundances and diversity of Fragilariceae and Aulacoseiraceae. In particular, the genetic approach detected hidden within-lake variations of fragilarioids in glacial lakes and dominance of centric Aulacoseira species, whereas Lindavia ocellata was predominant using morphology. In thermokarst lakes, sequence types and valve counts also detected high diversity of Fragilariaceae, which followed the vegetation gradient along the treeline. Ordination analyses of the genetic data from glacial and thermokarst lakes suggest that concentrations of sulfate (SO42-), an indicator of the activity of sulfate-reducing microbes under anoxic conditions, and bicarbonate (HCO3-), which relates to surrounding vegetation, have a significant influence on diatom community composition. For thermokarst lakes, we also identified lake depth as an important variable, but SO42- best explains diatom diversity derived from genetic data, whereas HCO3- best explains the data from valve counts. Higher diatom diversity was detected in glacial lakes, most likely related to greater lake age and different edaphic settings, which gave rise to diversification and endemism. In contrast, small, dynamic thermokarst lakes are inhabited by stress-tolerant fragilarioids and are related to different vegetation types along the treeline ecotone. Our study demonstrated that genetic investigations of lake sediments can be used to interpret climate and environmental responses of diatoms. It also showed how lake type affects diatom diversity, and that such genetic analyses can be used to track diatom community changes under ongoing warming in the Arctic.}, language = {en} } @misc{WestburyHartmannBarlowetal.2018, author = {Westbury, Michael V. and Hartmann, Stefanie and Barlow, Axel and Wiesel, Ingrid and Leo, Viyanna and Welch, Rebecca and Parker, Daniel M. and Sicks, Florian and Ludwig, Arne and Dalen, Love and Hofreiter, Michael}, title = {Extended and continuous decline in effective population size results in low genomic diversity in the world's rarest hyena species, the brown hyena}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {589}, issn = {1866-8372}, doi = {10.25932/publishup-41413}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-414132}, pages = {13}, year = {2018}, abstract = {Hyenas (family Hyaenidae), as the sister group to cats (family Felidae), represent a deeply diverging branch within the cat-like carnivores (Feliformia). With an estimated population size of <10,000 individuals worldwide, the brown hyena (Parahyaena brunnea) represents the rarest of the four extant hyena species and has been listed as Near Threatened by the IUCN. Here, we report a high-coverage genome from a captive bred brown hyena and both mitochondrial and low-coverage nuclear genomes of 14 wild-caught brown hyena individuals from across southern Africa. We find that brown hyena harbor extremely low genetic diversity on both the mitochondrial and nuclear level, most likely resulting from a continuous and ongoing decline in effective population size that started similar to 1 Ma and dramatically accelerated towards the end of the Pleistocene. Despite the strikingly low genetic diversity, we find no evidence of inbreeding within the captive bred individual and reveal phylogeographic structure, suggesting the existence of several potential subpopulations within the species.}, language = {en} } @article{WestburyHartmannBarlowetal.2018, author = {Westbury, Michael V. and Hartmann, Stefanie and Barlow, Axel and Wiesel, Ingrid and Leo, Viyanna and Welch, Rebecca and Parker, Daniel M. and Sicks, Florian and Ludwig, Arne and Dalen, Love and Hofreiter, Michael}, title = {Extended and continuous decline in effective population size results in low genomic diversity in the world's rarest hyena species, the brown hyena}, series = {Molecular biology and evolution}, volume = {35}, journal = {Molecular biology and evolution}, number = {5}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0737-4038}, doi = {10.1093/molbev/msy037}, pages = {1225 -- 1237}, year = {2018}, abstract = {Hyenas (family Hyaenidae), as the sister group to cats (family Felidae), represent a deeply diverging branch within the cat-like carnivores (Feliformia). With an estimated population size of <10,000 individuals worldwide, the brown hyena (Parahyaena brunnea) represents the rarest of the four extant hyena species and has been listed as Near Threatened by the IUCN. Here, we report a high-coverage genome from a captive bred brown hyena and both mitochondrial and low-coverage nuclear genomes of 14 wild-caught brown hyena individuals from across southern Africa. We find that brown hyena harbor extremely low genetic diversity on both the mitochondrial and nuclear level, most likely resulting from a continuous and ongoing decline in effective population size that started similar to 1 Ma and dramatically accelerated towards the end of the Pleistocene. Despite the strikingly low genetic diversity, we find no evidence of inbreeding within the captive bred individual and reveal phylogeographic structure, suggesting the existence of several potential subpopulations within the species.}, language = {en} } @article{RjoskRichterLuedtkeetal.2017, author = {Rjosk, Camilla and Richter, Dirk and Luedtke, Oliver and Eccles, Jacquelynne Sue}, title = {Ethnic Composition and Heterogeneity in the Classroom: Their Measurement and Relationship With Student Outcomes}, series = {The journal of educational psychology}, volume = {109}, journal = {The journal of educational psychology}, publisher = {American Psychological Association}, address = {Washington}, issn = {0022-0663}, doi = {10.1037/edu0000185}, pages = {1188 -- 1204}, year = {2017}, abstract = {This study explores various measures of the ethnic makeup in a classroom and their relationship with student outcomes. We examine whether measures of ethnic diversity are related to achievement (mathematics, reading) and feeling of belonging with one's peers over and above commonly investigated composition characteristics. Multilevel analyses were based on data from a representative sample of 18,762 elementary school students in 903 classrooms. The proportion of minority students and diversity measures showed negative associations with student outcomes in separate models. Including diversity measures and the proportion of minority students, diversity of minority students mostly lost its significance. However, the results suggest that diversity measures may provide additional information over and above other classroom characteristics for some student outcomes. The various measures of diversity led to comparable results. (PsycINFO Database Record (c) 2017 APA, all rights reserved)}, language = {en} } @phdthesis{MeyerLucht2009, author = {Meyer-Lucht, Yvonne}, title = {Does variability matter? Major histocompatibility complex (MHC) variation and its associations to parasitism in natural small mammal populations}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-36419}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {The adaptive evolutionary potential of a species or population to cope with omnipresent environmental challenges is based on its genetic variation. Variability at immune genes, such as the major histocompatibility complex (MHC) genes, is assumed to be a very powerful and effective tool to keep pace with diverse and rapidly evolving pathogens. In my thesis, I studied natural levels of variation at the MHC genes, which have a key role in immune defence, and parasite burden in different small mammal species. I assessed the importance of MHC variation for parasite burden in small mammal populations in their natural environment. To understand the processes shaping different patterns of MHC variation I focused on evidence of selection through pathogens upon the host. Further, I addressed the issue of low MHC diversity in populations or species, which could potentially arise as a result from habitat fragmentation and isolation. Despite their key role in the mammalian evolution the marsupial MHC has been rarely investigated. Studies on primarily captive or laboratory bred individuals indicated very little or even no polymorphism at the marsupial MHC class II genes. However, natural levels of marsupial MHC diversity and selection are unknown to date as studies on wild populations are virtually absent. I investigated MHC II variation in two Neotropical marsupial species endemic to the threatened Brazilian Atlantic Forest (Gracilinanus microtarsus, Marmosops incanus) to test whether the predicted low marsupial MHC class II polymorphism proves to be true under natural conditions. For the first time in marsupials I confirmed characteristics of MHC selection that were so far only known from eutherian mammals, birds, and fish: Positive selection on specific codon sites, recombination, and trans-species polymorphism. Beyond that, the two marsupial species revealed considerable differences in their MHC class II diversity. Diversity was rather low in M. incanus but tenfold higher in G. microtarsus, disproving the predicted general low marsupial MHC class II variation. As pathogens are believed to be very powerful drivers of MHC diversity, I studied parasite burden in both host species to understand the reasons for the remarkable differences in MHC diversity. In both marsupial species specific MHC class II variants were associated to either high or low parasite load highlighting the importance of the marsupial MHC class II in pathogen defence. I developed two alternative scenarios with regard to MHC variation, parasite load, and parasite diversity. In the 'evolutionary equilibrium' scenario I assumed the species with low MHC diversity, M. incanus, to be under relaxed pathogenic selection and expected low parasite diversity. Alternatively, low MHC diversity could be the result of a recent loss of genetic variation by means of a genetic bottleneck event. Under this 'unbalanced situation' scenario, I assumed a high parasite burden in M. incanus due to a lack of resistance alleles. Parasitological results clearly reject the first scenario and point to the second scenario, as M. incanus is distinctly higher parasitised but parasite diversity is relatively equal compared to G. microtarsus. Hence, I suggest that the parasite load in M. incanus is rather the consequence than the cause for its low MHC diversity. MHC variation and its associations to parasite burden have been typically studied within single populations but MHC variation between populations was rarely taken into account. To gain scientific insight on this issue, I chose a common European rodent species. In the yellow necked mouse (Apodemus flavicollis), I investigated the effects of genetic diversity on parasite load not on the individual but on the population level. I included populations, which possess different levels of variation at the MHC as well as at neutrally evolving genetic markers (microsatellites). I was able to show that mouse populations with a high MHC allele diversity are better armed against high parasite burdens highlighting the significance of adaptive genetic diversity in the field of conservation genetics. An individual itself will not directly benefit from its population's large MHC allele pool in terms of parasite resistance. But confronted with the multitude of pathogens present in the wild a population with a large MHC allele reservoir is more likely to possess individuals with resistance alleles. These results deepen our understanding of the complex causes and processes of evolutionary adaptations between hosts and pathogens.}, language = {en} }